genirq/timings: Add infrastructure for estimating the next interrupt arrival time
An interrupt behaves with a burst of activity with periodic interval of time followed by one or two peaks of longer interval. As the time intervals are periodic, statistically speaking they follow a normal distribution and each interrupts can be tracked individually. Add a mechanism to compute the statistics on all interrupts, except the timers which are deterministic from a prediction point of view, as their expiry time is known. The goal is to extract the periodicity for each interrupt, with the last timestamp and sum them, so the next event can be predicted to a certain extent. Taking the earliest prediction gives the expected wakeup on the system (assuming a timer won't expire before). Signed-off-by:Daniel Lezcano <daniel.lezcano@linaro.org> Signed-off-by:
Thomas Gleixner <tglx@linutronix.de> Cc: Nicolas Pitre <nicolas.pitre@linaro.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Hannes Reinecke <hare@suse.com> Cc: Vincent Guittot <vincent.guittot@linaro.org> Cc: "Rafael J . Wysocki" <rafael@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Bjorn Helgaas <bhelgaas@google.com> Link: http://lkml.kernel.org/r/1498227072-5980-2-git-send-email-daniel.lezcano@linaro.org
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